Bugfix: occasional crash on iCloud updates
Bugfix: limit the extent of the tableView when the keyboard is on screen to keep all cells accessible.
Bugfix: prevent ugly grey square when cell is tapped in the wrong spot
Bugfix: minor mathematical error
Bugfix: selected cell scrolls to top of table view to prevent its being obscured by the keyboard
Optimisation: cache all NSFetchController changes and perform in one bulk operation.
Bugfix: table now correctly sized when displayed on a 3.5” iPhone screen